U.S. patent number 4,982,274 [Application Number 07/284,072] was granted by the patent office on 1991-01-01 for heat pipe type cooling apparatus for semiconductor.
This patent grant is currently assigned to The Furukawa Electric Co., Ltd.. Invention is credited to Takashi Murase, Suemi Tanaka.
United States Patent |
4,982,274 |
Murase , et al. |
January 1, 1991 |
Heat pipe type cooling apparatus for semiconductor
Abstract
A heat pipe type cooling apparatus for a semiconductor,
comprises a plurality of first copper pipes, each of the first
pipes having a plurality of V-shaped grooves formed in an inner
surface thereof and arranged in a circumferential direction
thereof, and a plurality of second copper pipes, each of the second
pipes having a plurality of second grooves formed in an inner
surface thereof, each of the second grooves having an opening
narrower than an inner part thereof. A plurality of ceramic pipes
connect the first pipes and the second pipes, through intermediate
pipes made of a nickel-iron alloy. One end of each of the second
pipes is inserted in a metal block on which a semiconductor is
mounted.
Inventors: |
Murase; Takashi (Yokohama,
JP), Tanaka; Suemi (Nishinomiya, JP) |
Assignee: |
The Furukawa Electric Co., Ltd.
(Tokyo, JP)
|
Family
ID: |
23088744 |
Appl.
No.: |
07/284,072 |
Filed: |
December 14, 1988 |
Current U.S.
Class: |
257/706;
165/104.33; 257/714; 257/717; 257/E23.088 |
Current CPC
Class: |
F28D
15/0275 (20130101); F28D 15/046 (20130101); H01L
23/427 (20130101); F28F 1/32 (20130101); H01L
2924/09701 (20130101); F28F 2265/30 (20130101); H01L
2924/0002 (20130101); H01L 2924/0002 (20130101); H01L
2924/00 (20130101) |
Current International
Class: |
H01L
23/427 (20060101); H01L 23/34 (20060101); H01L
025/04 () |
Field of
Search: |
;357/81,82
;165/104.33 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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3709006C |
|
Jul 1988 |
|
DE |
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55-156350 |
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Dec 1980 |
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JP |
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56-108098 |
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Aug 1981 |
|
JP |
|
56-122152 |
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Sep 1981 |
|
JP |
|
60-57956 |
|
Apr 1985 |
|
JP |
|
Primary Examiner: Hille; Rolf
Assistant Examiner: Loke; Steven
Attorney, Agent or Firm: Frishauf, Holtz, Goodman &
Woodward
Claims
What is claimed is:
1. A heat pipe type cooling apparatus for a semiconductor,
comprising:
a plurality of first metal pipes which extend substantially
parallel to each other, and one end of each of which is open, each
of said first metal pipes having a plurality of first grooves
formed in an inner surface thereof, each of said first grooves
extending into said first metal pipes in the thickness direction of
said first metal pipes and having a bottom portion within the
thickness of said first metal pipes, each of said first grooves
having an opening at the innermost surface of said first metal
pipes which is broader than an interior portion of said first
grooves;
a plurality of second metal pipes which extend substantially
parallel to each other, one end of each of which is closed to
provide a closed-end system and the other end of each of which is
open, each of said second metal pipes having a plurality of second
grooves formed in an inner surface thereof, each of said second
grooves extending into said second metal pipes in the thickness
direction of said second metal pipes and having an inner and bottom
portion within the thickness of said second metal pipes, each of
said second grooves having an opening at the innermost surface of
said second metal pipes which is narrower than the inner portion of
said second grooves;
an electrically insulating working liquid received in said first
and second metal pipes;
a plurality of electrically insulating pipes, each connecting said
one open end of said first metal pipes to said other open end of a
corresponding one of said second metal pipes so as to allow the
interiors of said first and second metal pipes to communicate with
each other, each of said first and second metal pipes, each of said
electrically insulating pipes and said electrically insulating
working liquid comprising a closed-end heat pipe assembly; and
a conductive block to which said one closed end of each of said
second metal pipes is connected, said conductive block having a
receiving surface for directly receiving a semiconductor which is
to be cooled thereon, without any intermediary between said
receiving surface and said semiconductor which is to be cooled.
2. An apparatus according to claim 1, further comprising a
plurality of fins connected to said first metal pipes for
dissipating heat from said first metal pipes.
3. An apparatus according to claim 2, wherein the other end of each
of said first metal pipes is tapered and formed into a
hemispherical shape, and has a nozzle formed thereon.
4. An apparatus according to claim 2, wherein the other end of each
of said first metal pipes is tapered and formed into a conical
shape, and has a nozzle formed thereon.
5. An apparatus according to claim 1, wherein said first grooves
formed in said first metal pipes are V-shaped grooves.
6. An apparatus according to claim 5, wherein said second grooves
formed in said second metal pipes are partially circular
grooves.
7. An apparatus according to claim 1, wherein said second grooves
formed in said second metal pipes are partially circular
grooves.
8. An apparatus according to claim 1, wherein said heat pipe
assembly includes a vibration damping member formed substantially
midway along a longitudinal direction of said heat pipe
assembly.
9. An apparatus according to claim 6, wherein said said vibration
damping member is coupled to said first metal pipe, and includes a
bellowslike portion constituting part of said first metal pipe.
10. An apparatus according to claim 9, wherein said damping member
includes a plurality of said bellowslike portions, each coupled to
a respective first metal pipe.
11. An apparatus according to claim 10, wherein said bellowslike
portions are made of the same material as that of said first metal
pipes, and are integrally formed therewith.
12. An apparatus according to claim 7, wherein said bellowslike
portion is made of the same material as that of said first metal
pipe, and is integrally formed therewith.
13. A heat pipe type cooling apparatus for a semiconductor,
comprising:
a plurality of first pipes made of cooper, one end of each of which
is open, each of said first pipes having a plurality of first
V-shaped grooves formed in an inner surface thereof and arranged in
a circumferential direction thereof, said V-shaped grooves
extending into said first pipes in the thickness direction of said
first pipes and having the widest portions of said V-shaped grooves
at the inner surface of said first pipes;
a plurality of second pipes made of an element selected from the
group consisting of aluminum and copper, one end of each of which
is closed to provide a closed-end system and the other end of each
of which is open, each of said second pipes having a plurality of
second grooves formed in an inner surface thereof, each of said
second grooves extending into said second pipes in the thickness
direction of said second pipes and having an inner and bottom
portion within the thickness of said second pipes, each of said
second grooves having an opening at the innermost surface of said
second pipes which is narrower than the inner portion of said
second grooves;
an electrically insulating working liquid provided in said first
and second pipes;
a plurality of ceramic pipes arranged between said one open end of
each of said first pipes and said other open end of a corresponding
one of said second pipes;
a plurality of intermediate pipes made of an element selected from
the group consisting of Koval and a nickel-iron alloy, and
respectively coupled between at least one end of said ceramic pipes
and at least one of said first and second pipes, each of said first
and second pipes, said working liquid, each of said ceramic pipes,
and each of said intermediate pipes comprising a closed-end heat
pipe assembly; and
a conductive block having an end face in which said one closed end
of each of said second heat pipes is inserted, and said conductive
block having a receiving surface for directly receiving a
semiconductor which is to be cooled thereon, without any
intermediary between said receiving surface and said semiconductor
which is to be cooled.
14. An apparatus according to claim 9, wherein said first pipe
includes a bellowslike vibration damping portion formed near said
intermediate pipe.
15. An apparatus according to claim 13, wherein said intermediate
pipes are coupled to each end of said ceramic pipes, between said
ceramic pipes and said first and second pipes, respectively.
16. A heat pipe type cooling apparatus for a semiconductor,
comprising:
a plurality of first metal pipes which extend substantially
parallel to each other, and one end of each of which is open, each
of said first metal pipes having a plurality of first grooves
formed in an inner surface thereof, each of said first grooves
extending into said first metal pipes in the thickness direction of
said first metal pipes and having a bottom portion within the
thickness of said first metal pipes, each of said first grooves
having an opening at the innermost surface of said first metal
pipes which is broader than an interior portion of said first
grooves;
a plurality of second metal pipes which extend substantially
parallel to each other, one end of each of which is closed to
provide a closed-end system and the other end of each of which is
open, each of said second metal pipes having a plurality of second
and third grooves formed in an inner surface thereof to form
boiling cores, each of said second and third grooves being
generally V-shaped and extending into said second metal pipes in
the thickness direction of said second metal pipes having an
opening at the inner most surface of said second metal pipes which
is broader than an inner part of the respective second and third
grooves thereof, said second grooves extending in a first direction
and said third grooves extending in a second direction so as to
cross or intersect with said second grooves, whereby said first and
second grooves which are crossed or intersect with one another form
a large number of small recesses so that a number of boiling cores
defined by said intersecting second and third grooves are
increased;
an electrically insulating working liquid received in said first
and second metal pipes;
a plurality of electrically insulating pipes, each connecting said
one open end of each of said first metal pipes to said other closed
end of a corresponding one of said second metal pipes so as to
allow the interiors of said first and second metal pipes to
communicate with each other, each of said first and second metal
pipes, each of said electrically insulating pipes and said
electrically insulating working liquid comprising a closed heat
pipe assembly; and
a conductive block to which said one closed end of each of said
second metal pipes is connected, and said conductive block having a
receiving surface for directly receiving a semiconductor which is
to be cooled thereon, without any intermediary between said
receiving surface and said semiconductor which is to be cooled.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a heat pipe type cooling apparatus
for semiconductors.
2. Description of the Related Art
As disclosed in Japanese Patent Disclosure (Kokai) No. 60-57956 by
the present inventors, a cooling apparatus for cooling power
semiconductors such as a thyristor by using a heat pipe is already
known. As shown in Figs. 1A and lB, in this heat pipe type cooling
apparatus for semiconductors, fins 2, each of which is made of a
metal, such as aluminum or copper, having a high thermal
conductivity, extend from heat pipes 1, each of which is made of a
metal, such as copper, having a high thermal conductivity so as to
constitute a heat dissipation portion. The lower ends of the heat
pipes are inserted in metal block 3 made of a metal, such as copper
or aluminum, having a high thermal conductivity. With this
arrangement, loss heat from semiconductor 4 such as a thyristor
attached to the metal block is transferred to the heat pipes, and
is cooled down naturally or forcibly by a fan through the fines,
thereby increasing efficiency of the semiconductor. Terminal 5 for
extracting a current is attached to the block as needed. Since a
surface of a semiconductor such as a thyristor generally has a
potential, a current flows to the heat dissipation portion through
the metal heat pipes. Therefore, handling of the heat pipe type
cooling apparatus is dangerous depending on operating conditions.
Especially, since such an apparatus is often mounted in a vehicle
such as a train and used as a cooling apparatus for an inverter
thyristor, a problem of electrical safety is inevitably posed. For
this reason, an insulating plate made of a ceramic material, such
as aluminum nitride, having a relatively high thermal conductivity
is arranged between the semiconductor such as a thyristor and the
metal block so as to perform electrical insulation. However, the
above aluminum nitride insulating plate poses problems in terms of
thermal performance, withstand voltage function, mechanical
strength, reliability, and the like.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a heat pipe
type cooling apparatus which can prevent a current from flowing to
a heat dissipation portion and is excellent in thermal performance,
mechanical strength, and reliability.
According to the present invention, there is provided a heat pipe
type cooling apparatus for a semiconductor, comprising a plurality
of first metal pipes which extend substantially parallel to each
other, and one end of each of which is open, each of the first
metal pipes having a plurality of first grooves formed in an inner
surface thereof, each of the first grooves having an opening
broader than an inner part thereof, a plurality of second metal
pipes which extend substantially parallel to each other, one end of
each of which is closed and the other end of each of which is open,
each of the second metal pipes having a plurality of second grooves
formed in an inner surface thereof, each of the second grooves
having an opening narrower than an inner part thereof, a plurality
of electrically insulating pipes, each connecting one end of each
of the first metal pipes to the other end of a corresponding one of
the second metal pipes so as to allow the first and second metal
pipes to communicate with each other, a conductive block to which
one end of each of the second metal pipes is connected and a
semiconductor is attached, and an electrically insulating working
liquid supplied into the metal pipes.
Said insulating pipes for connecting the first and second metal
pipes are constituted by electrically insulating pipes each made of
an inorganic material such as alumina, magnesia, glass, ceramic,
and the like.
Both the heat dissipation and absorption portions of the metal
pipes may be made of a metal having a high thermal conductivity,
such as copper and aluminum. The grooves each having an opening and
a hollow portion therein are formed in the inner surface of each
second metal pipe, so that the working liquid may flow into the
hollow portion from the opening, and is heated, so that core
boiling occurs, and the liquid is evaporated upon generation of
bubbles. In this case, the core boiling is promoted because of the
narrow opening and broad hollow portion, and hence evaporation of
the working liquid is also promoted. In addition, since V-shaped
grooves are formed in the first metal pipe, convection of the
working liquid is accelerated while the surface area is increased
and a condensation effect is enhanced. The number of the grooves is
determined according to the property of working liquid. It is
preferable that each metal pipe constituting the heat dissipation
portion has an upper end tapered in a hemispherical or conical
shape, and has a nozzle at its distal end. With this arrangement,
the V-shaped grooves are formed in the inner surface of each metal
pipe so as to extend to its end portion, and hence efficiency as a
heat pipe can be increased. The nozzles formed at the ends of the
metal pipes are used to supply the working liquid. The lower end of
each second metal pipe is preferably tapered in a hemispherical or
conical shape. With this arrangement, similar to the heat
dissipation portion, the grooves formed in the inner surface of the
metal pipe extend to its end portion, thus increasing evaporation
efficiency.
According to the heat pipe type cooling apparatus for a
semiconductor of the present invention, the heat pipes may be
vertically or horizontally arranged. Especially, if they are
horizontally arranged, since the grooves are formed in the inner
surfaces of the metal pipes and these grooves effectively function
as wicks, the heat dissipation characteristics can be improved.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1A and 1B show a conventional heat pipe cooling apparatus, in
which FIG. 1A is a front view and FIG. 2B is a sectional view;
FIGS. 2A to 2F show a heat pipe cooling apparatus according to an
embodiment of the present invention, in which FIG. 2A is a front
view,
FIG. 2B is a sectional view taken along line 2B--2B of FIG. 2A,
FIG. 2C is a sectional view taken along line 2C--2C of FIG. 2A,
FIG. 2D is a plan view,
FIG. 2E is a partially cutaway side view showing an insulating pipe
connecting a first metal pipe to a second metal pipe and
FIG. 2F is a partially cutaway perspective view of a part of a
first metal pipe;
FIG. 3 is a graph showing a measurement result of characteristics
of the apparatus according to the embodiment; and
FIG. 4 is a partially cutaway perspective view of a part of a
modified second metal pipe.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
A cooling apparatus according to an embodiment of the present
invention and a method of manufacturing the same will be described
below with reference to FIGS. 2A to 2F. The upper end portion of
each metal pipe 11 made of such as copper and having an outer
diameter of 15.88 mm is formed into a hemispherical shape by
spinning. Pipe 11 has an inner surface in which a large number of
V-shaped linear grooves 12 inclined against the axial direction L
of pipe 11 by a small angle .alpha. are formed at a depth of 0.3 mm
and a pitch of 0.6 mm in the circumferential direction by plug
drawing. The inclined angle .alpha. is preferably
2.about.10.degree. and more preferably 3.about.7: The hemispherical
end portion is further processed by spinning so as to form nozzle
13 having a small hole. With this process, first metal pipe 11
constituting a heat dissipation portion is formed. Subsequently, a
large number of V-shaped linear inclined grooves are formed in the
inner surface of another metal pipe made of copper at a depth of
1.0 mm and a pitch of 1.5 mm by plug drawing. Thereafter, grooves
16, each of which has opening 14 and hollow portion 15 located
therein and having a larger diameter than opening 14, are formed in
the grooves at a depth of 0.65 mm and a pitch of 1.5 mm by plug
drawing using a spherical plug. Similarly, the lower end of the
pipe is formed into a hemispherical shape by spinning, and is
sealed by welding, thereby manufacturing second metal pipe 17.
The lower end, i.e., the opening end, of first metal pipe 11 is
connected to the upper end, i.e., the opening end, of second metal
pipe 17 by using electrically insulating pipe 18. In this
embodiment, as shown in FIG. 2E, intermediate pipes or flanged tube
19 made of a material having a similar heat-expansion coefficient
to the material of insulating pipe 18 such as a 42Ni-Fe68 alloy or
koral are brazed to both the ends of insulating pipe 18 in advance.
Metal pipes 11 and 17 are respectively brazed to intermediate pipes
19. This insulating pipe is made of a ceramic material such as
Al.sub.2 0.sub.3. When two metal pipes 11 and 17 are connected to
each other in this manner, a heat pipe assembly is formed.
Subsequently, one end portion of each heat pipe assembly, which has
a length of 120 mm, is inserted into a corresponding one of four
blind holes formed in one end surface of metal block 20 made of
copper or aluminum, by drilling, and is brazed to block 20 using a
soft brazing material, thereby forming a heat absorption portion.
The blind hole of metal block 20 may be alternately made by forming
a through hole in metal block 20 and then packing one end of the
through hole with a plug. A working liquid having an electrically
insulation properties, such as Freon, is supplied from nozzle 13 at
the upper end of metal pipe 11. Nozzle 13 is then caulked by a
pressing jig and its upper end is sealed by TIG welding in a
liquid-tight state.
In the embodiment, each first metal pipe 11 has bellowslike elastic
portion 11a near insulating pipe 18, as shown in detail in FIG. 2E.
This arrangement can prevent damage to the connected portions of
the metal pipes due to vibrations when this apparatus is used in a
vehicle. Elastic portion 11 May be formed by bending part of metal
pipe 11 or by attaching an elastic portion formed by bending to
metal pipe 11. A large number of aluminum fins 21 are then formed
on an upper portion of the metal pipe so as to constitute a heat
dissipation portion.
The heat pipe cooling apparatus for semiconductors manufactured in
this manner has the following structure. A large number of fins
extending from metal pipe 11 constitute the heat dissipation
portion, metal pipes 17 inserted into metal block 20 constitute the
heat absorption portion, and metal pipes 11 and 17 are connected to
each other through electrically insulating pipes 18.
A loss heat generated by semiconductor 22 such as a thyristor
attached to metal block 20 is transferred to each metal pipe 17
through metal block 20, and is dissipated by the heat dissipation
portion of metal pipes 11. In this case, since insulating pipes 18
are respectively arranged between metal pipes 11 and 17, the heat
dissipation portions are electrically insulated, and hence only the
heat is transferred, thus eliminating the danger of an electrical
shock. In addition, since an electrically insulating liquid is used
as the working liquid, safety operation can be ensured. Heat
dissipation performance is increased because of the V-shaped
grooves formed in the inner surface of each first metal pipe 11 of
the heat dissipation portion as shown in the cross sectional view
of FIG. 2B. In addition, heat absorption performance is increased
because of openings 14 formed in the inner surface of each second
metal pipe 17 of the heat absorption portion and grooves 16 having
hollow portions 15, which are formed deep inside openings 14.
FIG. 3 shows a result obtained by checking characteristics of the
above-described cooling apparatus of the present invention and of a
comparative example which has the similar construction and
dimensions to the embodiment except that each second metal pipe has
the same V-shaped grooves as those of first metal pipe.
In this test, two cooling apparatuses were used as a pair, and a
thyristor having a post diameter of 75 mm was vertically inserted
into each cooling apparatus. Then, heat dissipation performance
(heat resistance) was checked by operating each thyristor at a
power loss (loss heat) of 200 to 2,000 W while cooling each
apparatus at a wind velocity of 3 m/s at the front surface.
In the embodiment (curve a) (having different grooves in the heat
dissipation and absorption portions), it was apparent, as shown in
FIG. 3, that the heat dissipation performance was improved as
compared with the comparative example having identical grooves in
both the portions (it was found that the heat dissipation
performance was improved especially during a low heat flux of 500 W
or less, i.e., during a low power loss period). During a low power
loss period of 500 W (2.27 W/cm.sup. 2), the heat resistance was
decreased by 18.9%, i.e., from 0.037 to 0.03.degree. C/W (the heat
dissipation performance was increased). The heat resistance was
decreased by 25.5%, i.e., from 0.047 to 0.035.degree. C/W at 200 W
(0.91 W/cm.sup.2).
In the above-described embodiment, accurately V-shaped grooves are
formed in first metal pipes 11. However, the present invention is
not limited to this arrangement as long as the sectional area of
the opening of each groove is larger than that of any other part
thereof. In contrast to this, any groove can be formed in second
metal pipe 17 as long as it has a portion having a larger sectional
area than its opening, i.e., as long as it is narrowed at its
opening.
FIG. 4 shows a modification of a second metal pipe 17 in which
V-shaped grooves 16 are formed in the inner surface of the pipe 17
to cross with one another, so that a number of boiling cores may be
increased and each boiling core may be small.
According to the present invention, even if a semiconductor such as
a thyristor is directly attached to a surface of the metal block,
the potential of the thyristor is not transferred to the heat
dissipation portion because an intermediate portion of each heat
pipe is electrically insulated. Therefore, only heat is transferred
to the heat dissipation portion, and hence an electric shock can be
prevented. In addition, since the semiconductor can be directly
attached to the metal block, thermal performance can also be
improved.
Furthermore, grooves having a shape for promoting condensation
characteristics are formed in the inner surface of each metal pipe
at the fin-formed portion, whereas special or linear grooves or a
porous surface suitable for promoting boiling characteristics is
formed in the inner surface of each metal pipe of the heat
absorption portion (a thyristor mounting portion). Therefore, the
heat dissipation and absorption characteristics can be greatly
improved. As a result, a small apparatus can be realized.
Moreover, since the end portion of each metal pipe is formed into a
hemispherical or conical shape, the grooves can extend to the end.
As a result, an effective area can be increased compared with a
pipe having a flat end portion, thereby improving the performance
as a heat pipe.
* * * * *